In a large (1-gallon) saucepan or wok, add the oil, coconut cream, and curry pastes. Stir over medium-high heat until fragrant, about 2 minutes. Add the chicken pieces and stir to coat in the sauce, about one minute. Add the sugar, fish sauce, coconut milk, and stock, stir everything together and bring to a very gentle boil. This should take roughly 10 minutes. Once the chicken is fully cooked through, about 3 more minutes, stir in the sliced tofu and curry powder. Mixing well (but gently) to distribute the curry powder evenly. Lower the heat all the way to the lowest setting; keep the curry warm.